|  | 1.5 | Routing and the Different Classes of Routing Protocols
| 1.5.7 | IP routing protocols
At the network layer (Layer 3) of the OSI reference model, a router can use IP routing protocols to accomplish routing through the implementation of a specific routing protocol. Examples of IP routing protocols include: RIP-A distance-vector routing protocol IGRP-Cisco's distance-vector routing protocol OSPF-A link-state routing protocol EIGRP-A balanced-hybrid routing protocol Most routing protocols can be classified as one of two basic types: distance vector or link state. The distance-vector routing protocol determines the direction (vector) and distance to any link in the network. The link-state routing protocol (also called the shortest path first [SPF] protocol) approach re-creates the exact topology of the entire network (or at least the partition in which the router is situated). A third type of protocol, the balanced-hybrid protocol, combines aspects of the link-state and distance-vector protocols.